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Author Dai, Yafei ♦ Chowdhury, Sugata ♦ Blaisten-Barojas, Estela
Source arXiv.org
Content type Text
File Format PDF
Date of Submission 2009-12-06
Language English
Subject Domain (in DDC) Computer science, information & general works ♦ Natural sciences & mathematics ♦ Physics
Subject Keyword Condensed Matter - Mesoscale and Nanoscale Physics ♦ Condensed Matter - Materials Science ♦ Physics - Chemical Physics ♦ physics:cond-mat ♦ physics:physics
Abstract First-principles calculations are used to investigate the electronic properties of neutral and negatively charged n-pyrrole oligomers with n= 2-18. Chains of neutral oligomers are bent while the negatively charged oligomers become almost flat due to accumulation of negative charge at the end monomers. Several isomers of the short oligomers (n < 5) display negative electron affinity, although they are energetically stable. For longer oligomers with n > 5, the electron affinity turns positive, increasing with oligomer length. The doping of 12-pyrrole with lithium atoms is studied, showing that negative oxidation states are possible due to charge transfer from dopant to oligomer at locations close to dopant. These molecular regions support extra negative charge and exhibit a local structural change from benzenoid to quinoid in the C-C backbone conjugation. Additional calculations of neutral and doped polypyrrole are conducted showing that the doped infinite polymer chain displays a substantial reduction of the energy band gap and the appearance of dopant-based bands in the gap.
Educational Use Research
Learning Resource Type Article
Page Count 22


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